The long-range objectives of our research are to gain an insight into the mechanisms operative in the regulation of RNA synthesis in eukaryotic organisms and to assess the role of hormone-regulated RNA synthesis in the induction of tissue proliferation. The proposed research will focus on 1) the purification and characterization of RNA polymerase I from tissues representing normal and hormone-induced growth transitions, emphasizing the mechanism(s) by which auxin enhances RNA polymerase I activity, 2) mechanisms by which RNA polymerase I activity is modulated relative to rapid turnover of regulatory protein factors or by other agents such as ppGpp (or functionally similar compounds), 3) purification and characterization of protein phosphokinases, emphasizing studies on the develomental regulation of their activities and the phoshorylation of chromatin proteins, and 4) an assessment will be made of the nucleotide sequence complexity of RNAs transcribed in control and hormone-treated tissue from unique sequence DNA. These studies will finally be integrated into an analysis of mechanisms involved in the regulation of rRNA synthesis and ribosome formation as one of the earliest (causal?) events associated with the induction of tissue proliferation. Standard procedures of enzymology DNA-RNA hybridization, cell fractionation and the study of regulatory molecules will be used.